From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA786C433FE for ; Thu, 3 Feb 2022 08:39:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7213E8D0131; Thu, 3 Feb 2022 03:39:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A8B28D0129; Thu, 3 Feb 2022 03:39:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5709B8D0131; Thu, 3 Feb 2022 03:39:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0243.hostedemail.com [216.40.44.243]) by kanga.kvack.org (Postfix) with ESMTP id 44D838D0129 for ; Thu, 3 Feb 2022 03:39:35 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 077279368D for ; Thu, 3 Feb 2022 08:39:35 +0000 (UTC) X-FDA: 79100819910.27.D643000 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf06.hostedemail.com (Postfix) with ESMTP id 8535B180005 for ; Thu, 3 Feb 2022 08:39:34 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 40C4A1F3A5; Thu, 3 Feb 2022 08:39:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1643877573; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1IR6teMxtrUP9W66+J3byF21I9uPu8QtHmbbzm958a8=; b=eKuXArW/GmZea5Yf/lm7ZO4buRrMFTKqSZUKteMtfW1jfQr3GIbsOkTft8e+93oqR5oPoL /QLQuV81wxAu38gatOX1BJaJGpdFjcFTjQP2hW0YSHeq4yXi9Kt8f6qIb+Q+NdlU5LjRZT 1n4IX/k5uCHCRLniHIB6cn6YqMnhJYU= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 06FEDA3B83; Thu, 3 Feb 2022 08:39:32 +0000 (UTC) Date: Thu, 3 Feb 2022 09:39:32 +0100 From: Michal Hocko To: Mike Rapoport , Andrew Morton Cc: Wei Yang , linux-mm@kvack.org, LKML , David Hildenbrand , Alexey Makhalov , Dennis Zhou , Eric Dumazet , Oscar Salvador , Tejun Heo , Christoph Lameter , Nico Pache , Rafael Aquini Subject: Re: [PATCH 2/6] mm: handle uninitialized numa nodes gracefully Message-ID: References: <20220127085305.20890-1-mhocko@kernel.org> <20220127085305.20890-3-mhocko@kernel.org> <20220201024119.2ailcw4rp5thambz@master> <20220203002116.akpk5um5nkpeflve@master> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 8535B180005 X-Stat-Signature: q4yk3sbnootqjx3msa8rs58e6x4j7uh8 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b="eKuXArW/"; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf06.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspam-User: nil X-HE-Tag: 1643877574-282895 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu 03-02-22 09:23:20, Mike Rapoport wrote: > On Thu, Feb 03, 2022 at 12:21:16AM +0000, Wei Yang wrote: > > On Tue, Feb 01, 2022 at 10:54:37AM +0100, Michal Hocko wrote: > > >On Tue 01-02-22 02:41:19, Wei Yang wrote: > > >> On Thu, Jan 27, 2022 at 03:47:40PM +0100, Michal Hocko wrote: > > >> [...] > > >> >> > + /* > > >> >> > + * not marking this node online because we do not want to > > >> >> > + * confuse userspace by sysfs files/directories for node > > >> >> > + * without any memory attached to it (see topology_init) > > >> >> > + * The pgdat will get fully initialized when a memory is > > >> >> > + * hotpluged into it by hotadd_init_pgdat > > >> >> > + */ > > >> > > >> Hmm... which following step would mark the node online? On x86, the node is > > >> onlined in alloc_node_date(). This is not onlined here. > > > > > >The comment tries to explain that this happens during the memory > > >hotplug. Or maybe I have missed your question? > > > > > > > I am not sure for others, while the comment confused me a little. > > > > Currently in kernel, there are two situations for node online: > > > > * during memory hotplug > > * during sys-init > > > > For memory hotplug, we allocate pgdat and online node. And current hot-add > > process has already put them in two steps: > > > > 1. __try_online_node() > > 2. node_set_online() > > > > So emphasize "not online" node here, confuse me a little. It is a natural > > thing to not online node until it has memory. > > > > But from another point of view, the comment here is reasonable. During > > sys-init, we online node at the same time when creating pgdat. And even for > > memory-less node on x86, we online them too. > > > > Well, this is all about the comment. I have tried to grab may head but not > > come up with a better idea. > > > > Or maybe this is just my personal feeling, don't bother if no-one else feel > > like this. > > I shuffled the words a bit, maybe this sounds better not only to me :) > > /* > * We do not want to confuse userspace by sysfs files/directories for node > * without any memory attached to it, so this node is not marked as > * N_MEMORY and not marked online so that topology_init() won't create > * sysfs hierarchy for this node. The pgdat will get fully initialized by > * hotadd_init_pgdat() when memory is hotpluged into this node > */ Yes, I like this comment more than mine. Andrew could you replace it in your tree or should I repost the patch? Thanks! -- Michal Hocko SUSE Labs